Combination lock with cam follower positioned,cumulatively arrested tumbler elements



July 7, 1970 A. J. POTZICK 3,518,856

COMBINATION LOCK WITH CAM FOLLOWER POSITIONED, CUMULATIVELY ARRESTEDTUMBLER ELEMENTS Filed March 22, 1968 7 Sheets-Sheet 1 July 7, 1970 A.J. POTZiCK 3,518,856

COMBINATION LOCK WITH CAM FOLLOWER POSITIONED, CUMULATIVELY ARRESTEDTUMBLER ELEMENTS Filed March 22, 1968 7 Sheets-Sheet 2 SLIDER HOLDINGPIN \ RATCHET fla FLAPPER HOLDING STE PPING PAWL CAM

FOLLOWER W .2 WM zi gj A. J. POTZICK 3,518,856

ARRESTED TUMBLER ELEMENTS 7 Sheets-Sheet 5 m \Q MW MN July 7, 1970COMBINATION LOCK WITH CAM FOLLOWER POSITIONED, CUMULATIVELY Filed March22, 1968 July 7, 1970 A. J. PO'TZICK 3,513,856

COMBINATION LOCK WITH CAM FOLLOWER POSITIONED, CUMULATIVELY ARRESTEDTUMBLER ELEMENTS Filed March 22, 1968 7 She ets-Shee c 4 WWW f A. J.POTZICK FOL n TUMBLER July 7, 1970 3,518,856 COMBINATION LOCK WITH CAMLOWER POSITIONED, CUMULATIVELY ARRESTE ELEMENTS 7 Sheets-Sheet 5 FiledMarch 22, 1968 July 7, 1970 A. J. POTZICK 3,

COMBINATION LOCK WITH CAM FOLLOWER POSITIONED, CUMULATIVELY ARRESTEDTUMBLER ELEMENTS 7 Sheets-Sheet 6 Filed March 22, 1968 QMN m'm MAN July7, 1970 J, poTz cK 3,518,856

COMBINATION LOCK WITH CAM FOLLOWER POSITIONED, CUMULATIVELY ARRESTEDTUMBLER ELEMENTS Filed March 22, 1968 7 Sheets-Sheet United StatesPatent US. Cl. 70-499 40 Claims ABSTRACT OF THE DISCLOSURE In thiscombination lock, the dial turns a rotatable cam the movement of whichis followed by a set of cam followers. The motions of the respective camfollowers are in turn followed by tumbler elements. The elements can bearrested and held against further movement by holding means which isengageable with the respective elements in accumulating sequence. Fencemembers are interfittable with the respective tumbler elements if theelements have been arrested by the holding means in predeterminedpositions of alignment with the respective fence members. The membersare coupled to a lever which is connectable to a bolt thrower towithdraw the bolt, and they are moved toward the elements when the leveris moved. The elements and members must be interfitted before the levercan contact the bolt thrower. Combination changing structure is alsoprovided, which selectively permits changing the relative position ofthe members when they are interfitted with the elements.

This application is related to my copending application Ser. No.645,849, filed May 29, 1967, titled Combination Lock With Cam OperatedTumblers and Sequentially Engageable Tumbler Stops, now Pat. No.3,436,941, dated Apr. 8, 1969.

This invention relates to a combination lock which embodies newprinciples of operation.

Combination locks are responsive to a pre-established combination ofnumbers or letters which are set into the lock in sequence by operatinga dial. For many years combination locks have been based on mechanismswhich require that the dial be operated in a precise program or patternof turning movements to set the combination into the lock. Commonly theprogram has required turning the dial a specified number of turns in acertain direction, say four turns to the right, before stopping at thefirst number or letter of the combination, then a series of turns oneless in number in the opposite direction, e.g. three turns to the left,to the next number of the combination, followed by a decreasing sequenceof turns in opposite directions to set the other numbers into the lock.As a practical matter, the operation of such locks is undesirablycomplex because of the need to remember not only the combination butalso the dialing program and to execute it properly, including both thenumber and direction of turns required before stopping at each number ofthe combination. Because of this complexity, locks with combinations ofmore than four numbers or letters are rarely used, and such locks arerelatively slow to use and require careful attention in operation.

In contrast, the combination lock of this invention obviates the preciseprograms of dial turning previously required. The new lock can beoperated by turning the dial in either direction directly to the numbersor letters of the combination, and it does not require oppositerotations of the dial between successive numbers of the combination.Moreover, it does not require any prede- 3,518,856 Patented July 7, 1970termined number of turns, or indeed, any turns, of the dial betweensucceeding numbers of the combination. When the dial of the new lock hasbeen turned to a given number, that number is set into the lock by axialmovement of a dial shaft, for example by pushing the dial inwardly ashort distance. Hence the new lock operates with much greater simplicityand rapidity than combination locks of the past, because it requires nocomplex dial turning program. It thus makes practicable the use ofcombinations consisting of a larger set of numbers than previously. Forexample, a combination of seven numbers may be used to provide greaterresistance to surreptitious attack.

Prior combination locks have also tended to have a certain amount ofplay, or lack of sensitivity, which renders them responsive to imprecisedial settings; that is, they can be operated by dialing numbers merelyadjacent to the proper numbers of the combination. Thus a previous lockset to operate at the combination 2l-73-49 would usually operate if thedial were set at 20-74-50, thus significantly reducing the number oftrue combinations from the number of theoretical combinations.

In contrast, the new lock of this invention requires precise dialsetting. It will not open if set at numbers which are merely adjacentthe proper numbers, and it will not operate when the dial is positionedbetween integers. Each of the theoretical combinations is a truecombination.

Another difiiculty with prior combination locks has been that they haverequired parts made of plastic of low radiographic density to reducesusceptibility to surreptitious analysis by X-ray. However, the use ofplastic tumblers and other parts, while impeding radiographic analysis,does not provide the rigidity or stability afforded by metal parts.

In contrast, the lock of this invention affords generally equal orsuperior resistance to radiographic analysis, yet its structure is suchthat it can be made entirely out of metal, with its superior qualitiesof rigidity and stability.

In the conventional rotating tumbler combination locks of past, thetumblers are turned through lost motion couplings. A given tumbler movesonly when the lost motion is taken up.

In contrast, in the new combination lock, movable elements which mightbe likened to tumblers are positioned without lost motion, by camfollowers engaged with a rotatable cam.

Conventional tumbler operated combination locks are opened by settingthe tumblers in positions of alignment to interfit with a fence or barprojecting from the lever which withdraws the bolt. Conventionally thetumblers are positioned to receive the fence when the tumbler gates areoriented in a straight line opposite the fence.

In contrast, in the lock of this invention what might be likened to afence is comprised by a set of fence members which can be staggered withrespect to one another. The alignment positions of the tumbler elementswith the fence members with which they interfit is not limited to astraight line orientation.

In conventional key changeable tumbler operated locks, the combinationis changed by changing the position of the tumbler gate with respect tothe fly or drive means through which dial motion is imparted to thetumbler. In contrast, in the present lock the combination may be changednot by changing the tumbler elements, but by changing the positions ofthe fence members with which the tumbler elements are interfitted inpositions of alignment.

Moreover, the lock of this invention permits building in other variantsfrom lock to lock, besides the combination itself. The shape of the camcan readily be varied from lock to lock; the position and shape of thatportion of the interfitting means which is on the tumbler element candiffer from tumbler to tumbler, and from lock to lock, and the positionand shape of that portion of the interfitting means which is on thefence member can also differ.

Briefly described, in the present lock, the dial arbor rotates a cam themovement of which is followed by a set of cam followers. The camfollowers do not themselves act as tumblers, but they transmit motion ofthe cam to movable tumbler elements. The latter elements follow themotions of the respective cam followers, but are arrestable by holdingmeans so that when arrested, the elements no longer follow the movementsof the cam followers. The tumbler holding means is advanced inincrements, as by ratchet stepping means. Interfittable means arepresented in part on the tumbler elements and in part on fence membersassociated with the respective elements. These interfittable means canbe interfitted only if the tumbler elements have been arrested by theholding means in predetermined positions of alignment with therespective fence members.

The fence members are moved as a set toward and away from the tumblerelements by a coupling to a lever which is connectable to a bolt throwerto withdraw the bolt. Movement of the lever toward bolt withdrawingposition is blocked by disoriented tumbler elements, and connection towithdraw the bolt can only be made if all the tumbler elements areinterfitted with the respective fence members.

The combination of the lock is dependent upon the positions of the gatesor other interfitting means on the respective fence members. Optionalstructure is provided whereby the positions of the members with respectto one another can quickly be changed thereby to change the combination.This structure includes means for clamping the members in fixedpositions with respect to another, which means can be released when themembers have been interfitted with the respective tumbler elements andthe bolt has been withdrawn.

In some conventional tumbler operated locks, it is possible to tap thefence by means of rotating the gate in the bolt thrower under the noseof the lever. The camming engagement of the bolt thrower with the levernose gently lifts and lowers the fence off the tumbler peripheries andit is sometimes possible to obtain an indication of tumbler gateorientation in this manner.

Preferred structure in the present lock eliminates the possibility ofsuch tapping. The lever and the fence members are held away from thetumbler elements until all of the elements have been arrested by theholding means. As the last tumbler element is set, the lever is abruptlyreleased and it drops uncontrollably under the influence of a biasingspring toward the bolt thrower. If the proper combination has beendialed, so that all elements align with the fence members, then themembers can drop to the fullest extent. Only when that occurs will thenose of the lever contact the periphery of the bolt thrower. When thefence members drop to the fullest extent, the nose of the lever canenter a gate in the bolt thrower, and thereby be connected to withdrawthe bolt. The bolt thrower rotates at all times with the cam shaft andthe lock arbor, and need not be disconnected from the cam to withdrawthe bolt.

The details and features of the invention can best be further describedby reference to the drawings in which:

FIG. 1 is a perspective view of the preferred embodiment for thisinvention, showing the lock mounted to a safe door, partly broken away,with the lock cover removed and the bolt in extended position;

FIG. 2 is a simplified diagrammatic perspective illustrating majoroperating components of the lock;

FIG. 3 is a horizontal section taken along the line 33 in FIG. 1, withthe lock cover in place;

FIG. 4 is a vertical section taken along line 44 of FIG. 3, with thelock cover removed;

FIG. 5 is a vertical section taken along line 5-5 of FIG. 3;

FIG. 6 is a vertical section taken along line 66 of FIG. 4;

FIG. 7 is a vertical section similar to FIG. 6 but shows the tumblerholding means advanced to the position at which all of the respectivetumbler elements are held against movement and the lever is lowered forbolt retraction;

FIG. 8 is a vertical section taken on line 88' of FIG. 4;

FIG. 9 is a fragmentary horizontal section showing the fence set, takenon line 99 of FIG. 4;

FIG. 10 is a fragmentary horizontal section taken on line 1t)10 of FIG.5 showing the ratchet stepping means in starting position;

FIG. 11 is a fragmentary horizontal section similar to FIG. 3, but showsthe position of the ratchet stepping means when the arbor is pushed into set a dialed number;

FIG. 12 is a fragmentary section taken on line 1212 of FIG. 5 andillustrates the holding pawl of the stepping means;

FIG. 13 is a fragmentary section similar to FIG. 11 but illustrates theposition of the stepping means when the arbor is pulled out to clear thelock; and

FIG. 14 is a sectional view similar to FIG. 12 but illustrates theposition of the holding pawl when the arbor has been pulled out to clearthe lock.

GENERAL DESCRIPTION A general understanding of the components andoperation of a preferred form of this combination lock can be gained byreference to the structure diagrammatically shown in FIG. 2.

Rotating the lock dial (not shown in FIG. 2), turns a driver which isconnected to rotate cam means in the form of a disk-like cam. One end ofa pivoted cam follower is spring urged into contact with the shapedperiphery of the cam, and the cam follower turns and follows the camsurface as the driver is rotated. The other end of the cam followerbears upon and cams a movable tumbler element or slider in slidingmovement. The slider is spring urged against the cam follower and ispositioned in accordance with the position of the driver. The lockincludes a number of sets of cams, cam followers and sliders, only oneset of which is shown in FIG. 2 for purposes of explanation, the othersets being similar. Thus, as the lock dial is dialed to a certainnumber, the sliders are slid to various positions.

At the start of running the combination, rotation of the dial operatesall of the cam followers and sliders, but as the numbers are dialed andset, the respective sliders are arrested in sequence by tumbler holdingmeans or a slider holding pin which engages one of a series of holes ineach slider. This slider holding pin is mounted to and moves with aratchet. The ratchet is moved in steps to engage the sliders one by onein accumulating sequence, by setting the number by pushing axially onthe lock dial after each combination number is dialed. Pushing in on thedial moves a flapper or lever to which a stepping pawl is attached,which in turn pushes the ratchet forward one notch. When the ratchet hasbeen so advanced, a holding pawl prevents its return while the flapperis returned to its starting position, during which the stepping pawldrops back to its starting position, ready to advance the ratchet againupon the next push of the dial. This sequence causes the slider holdingpin to engage and arrest one slider, and is repeated for each slider asit is set in sequence.

A set of fence members are interfittable with the tumbler elements orsliders, each slider having a tooth which must be aligned with a gate onthe corresponding fence member before the bolt can be withdrawn; theslider teeth can be interfitted with the respective gates only if all ofthe teeth are properly aligned with the respective gates. The fencemembers are mounted for movement toward and away from the slider teeth,and for that purpose respond through a sliding coupling to movement of alever which is in turn connected to the bolt. The lever has a nose atone end which is engageable in a notch on a bolt throwing cam when thelever nose is properly oriented with respect to the notch, so that thebolt can be withdrawn.

During running of the combination the lever nose is prevented fromcontacting the bolt thrower notch by a leg which rests on the ratchet.When the last slider has been engaged by the pin (which corresponds tosetting of the last number), the lever leg is released or dropped offthe ratchet, and the lever drops toward the bolt throwing cam. The fencemembers respond to movement of the lever by moving toward the sliderteeth. If the sliders are correctly positioned, their teeth willinterfit with the respective fence member gates so that the lever nosecan drop into engagement with the bolt throwing cam notch. If thesliders are not properly oriented, then one or more of the disalignedslider teeth will block and prevent such interconnection of the lever tothe bolt throwing cam. When the lever is engaged in the bolt throwingcam, the bolt can be withdrawn by further rotation of the driver. Thelock is cleared by pulling out on the dial which releases the pawls fromthe ratchet, and a spring moves the slider holding pin out of engagementwith the sliders so that all the sliders again bear on the cam followersand are scrambled by the cams.

SPECIFIC DESCRIPTION The combination lock illustrated for purposes ofexplanation is seen in FIG. 1 as mounted adjacent the edge of a safedoor 20 with the lock bolt 21 in locked or extended position. The lockis manually operated through the dial means designated generally by 22in FIG. 1, by turning a dial or knob 23 having number graduations 24thereon alignable with an index mark (not shown) on a stationarysurrounding frame or housing 25. As will be described hereinafter, dial23 can both be rotated about its axis, and at certain positions can bepushed inwardly (that is, toward door 20) over a short limited distance.At one position dial 23 can be pulled outwardly a short distance. Theperiphery of dial 23 is marked with a series of numbers, preferably theintegers 0-9, but it will of course be appreciated that it can be markedwith more or fewer numbers or letter designations. The lock is furtherexplained hereinafter with specific reference to a lock dial having theintegers 0-9 on it.

The lock itself is mounted to the inside of the door 20, and iscontained within a housing or casing having a base or frame 28, mountedto safe door 20 by machine screws 29 which pass through bosses in thefour corners of the base 28. A lock cover 30 fits over and is secured tobase 28 through fixed internal components thereof by machine screws 31(see FIG. 3).

As best seen in FIG. 3, an operating shaft or arbor 33, to which dial 23is connected, extends into the lock casing through an opening in thebottom 34 of base 28 (the lock is frequently referred to herein as ifviewed with the bottom 34 of the base resting upon a horizontal surface,so that down refers to the direction toward base 34, while up refers tothe direction toward surface 35 of cover 30).

Arbor 33 is threaded adjacent its upper end, and a generally cylindricaldriver 36 is threaded onto it and keyed to the arbor by a key 37. Anopening 38 in top surface 35 may be provided so that key 37 can beinserted with the cover in place. Driver 36 is thus fixed to arbor 33for both rotation and axial movement therewith.

Just above the case bottom 34, driver 36 has an outer flange 39 having agroove 40 in its rim. A plurality of notches or cross-slots 44 arespaced equally around flange 39. The notches 44 correspond in angularposition and number to the integers on dial 23. A pin or stud 45 (seeFIG. 3), which may be formed on a corner boss of base 28, overhangs therim of driver flange 39, and this stud 45 is shaped so as to preventupward movement of arbor 33 and driver 36 (i.e., movement imparted tothe arbor by pushing dial 23 toward the safe door) by abutting drivingflange 39 unless the arbor is so oriented that one of the rim notches 44is aligned to receive stud 45 (see FIG. 4). Since the positions of thenotches 44 correspond to integer positions on the dial, stud 45 thusprevents the shaft 33 from being pushed inwardly unless the dial isaligned at a whole number. In this connection, it is noted that a smalllead or round may be provided on either stud 45 or the notches 44, tocam the driver into proper aligned position if it is only slightlydisali-gned when the dial is pushed in. These means insure that the dialcan be pushed in only at whole number positions and not at substantiallymisaligned fractional or intervening orientations.

"Pull-out movement of dial 23 that is, movement which tends to moveshaft 33 downwardly as seen in FIG. 3, is limited by pin or stud 46 onthe base 28. This stud 46 abuts the driver unless a single recess oropening 47 in the driver is aligned with the stud 46. The recess 47 ispreferably so located that the driver can be pulled out only when thedial is set at zero. A small taper can be provided to align the dial ifit is set just slightly out of exact position. By reason of theireffects in limiting axial movement of shaft 33, the studs 45 and 46 aresometimes referred to hereinafter as the push-in and pull-out pins,respectively. Interengagement of the driver flange 39 with the push-inpin 45 is shown in FIG. 11, and the interengagement of the driver flangewith the pull-out pin 46 is shown in FIG. 13.

The driver is urged to a centered or neutral axial position in which itdoes not engage either the push-in or pull-out pins 45 or 46, by biasingmeans in the form of a push-plate or flapper designated generally by 50(see FIGS. 3 and 5). The flapper 50 is pivoted at one side to base 28for rotation about an axle or shaft 51 which is transverse to the axisof arbor 33, and has a rounded outer end 52 which is engaged withindriver groove 40 and which slides therein as the driver is rotated.Opposed springs 53 and 54 engage opposite sides of flapper 50 and biasit toward its centered or neutral position.

The shank of driver 36 is provided with angularly spaced longitudinalgrooves 56 in each of which a ball key 57 rides. The ball keys provide asliding universal joint whereby the driver is connected to rotate ahollow cylindrical earn shaft 59 which loosely encircles the upper endof the driver 36 (see FIGS. 3 and 4). The balls 57 reside in recesses oropenings 60 in cam shaft 59. It can be seen that this interconnectionpermits the driver 36 to be shifted axially while at all times remainingrotationally interconnected to the cam shaft. This method ofinterconnection has the advantage of permitting some cooking of arbor 33with respect to the cam shaft, without causing binding thereof. Camshaft 59 is journalled at its upper and lower ends for rotation in amidplate and top plate designated by 64 and 65 respectively (see FIG.3), both of which are secured to the lock base 28 by means to bedescribed.

Midplate 64 is seated on bosses formed on base 28 and is located thereonby a stud or pin 68 and fastened to the base by screws 69 (FIGS. 3 and4). A bearing 70 may be press-fitted around the shaft opening inmidplate 64 to journal the cam shaft 59. Beneath midplate 64 a boltthrower or bolt-throwing cam 72 having a peripheral notch 73 is securedto cam shaft 59 for rotation therewith. At the upper end of the camshaft, above top plate 65, a spring retainer 75 is snapped into a groovein the cam shaft. Thus the bolt throwing cam 72 and spring retainer 75prevent axial movement of the cam shaft.

The top plate is spaced from and mounted to the midplate 64 by spacersleeves 76 on screws 77 (see FIGS.

1 and 4). The lock cover is secured by the machine screws 31 to the topplate 65 (see FIG. 3).

A set of cam disks 79, seven in number in the embodiment shown, aremounted on cam shaft 59 for rotation therewith. One suitable outlineform for the cam disks is shown in FIG. 4. It is convenient formanufacturing purposes (although not necessary) that all the cams besimilar in outline; to scramble them, the cams are differently orientedon the cam shaft. To that end the cams are splined to the cam shaftthrough points 80 on each cam which interfit with a series ofcorresponding grooves 81 formed on the cam shaft (see FIG. 4). Thevarious possible angular positions of the cams correspond to wholenumber settings of the dial 23. It can be seen that cam arrangement canreadily be varied from lock to lock simply by changing the camorientations on the cam shaft.

For each cam 79 there is provided a cooperating cam follower 83, atumbler element or slider 84, and a fence member 85 (see FIGS. 2 and 4),together with associated biasing springs to be described. Thus, in theembodiment shown there are seven such sets, each including a cam, camfollower, slider and fence member. The sliders form a pack or deck, asdo the fence members.

As seen in FIGS. 3 and 4, the cam follower 83 may be levers, and arepivotally mounted between the top plate and midplate on a post 87. Atone end, each cam follower 8-3 is provided with a rounded tip 88 whichis urged by a biasing spring 89 toward engagement with the periphery ofthe respective cam 79. At its other end each cam follower 83 has aslider-engaging camming surface 90.

As seen in FIG. 4, each slider 84 may be a flat, generally rectangular,slotted element supported for sliding movement on a pair of posts 94.Slider biasing springs urge the respective sliders 84 into engagementwith the tips 90 of the cam followers, and the sliders are thus cammedin sliding movement on posts 94 as the cam followers 83 follow movementof the cams 79 when the dial 23 is rotated. Each slider 84 has a fencemember interfitting portion such as a tooth 96 which, when properlyaligned, will engage or interfit with a cooperating interfitting portionsuch as a gate 97 on the respective fence member 85 (see FIGS. 2 and 4).Each slider 84 is also provided with a series of openings or holes 98which are aligned with holding means in the form of a shaft or pin 100at whole number dial positions. The respective sets of cam followers,sliders and associated springs 89 and 95 are separated from one anotherby interleaved spacers 101 (see FIG. 4) which are positioned by theposts 76 extending between the midand top plates. The springs 89 and 95are held in place by spring retainers 102, the retainers beingsandwiched between the spacerplates 101 and mounted on the posts 76. Thespacers 101 prevent each cam follower from engaging any cam or sliderother than that with which it is associated.

The cam follower biasing spring 89 is stronger than and overrides theslider biasing spring 95 so that the cam follower 83 rides on theperiphery of the cam 79. The slider 84 follows the movement of the camfollower 83 so long as the slider is not held in fixed positin byengagement of pin 100 in any of the holes 98 therein. When any slider isso held by pin 100, the respective cam follower will ride on the cameperiphery over the radial extent permitted within the limit imposed bythe fixed slider 84.

The holding pin 100, by which the respective sliders can be held inpositions corresponding to whole number dial settings, is mounted to andprojects toward the lock top surface 35 from an L-shaped bracket 105(see FIGS. 5 and 6). Bracket 105 is secured as by brazing onto a flatformed on one surface of a ratchet member designated by 106. Ratchetmember 106 is generally sleevelike, and is provided with a series ofsteps or V-shaped circumferential grooves 107 on its outside surface,for

engagement by pawls. The ratchet 106 is mounted for axial slidingmovement along a shaft 109 having an axis parallel to the axis of arbor33. Holding pin 100 is mounted to its bracket 105 parallel to shaft 109.Shaft 109 is received at one end in a recess of a boss 108 formed in thelock bottom 34 and is received at the other end in the lock top plate 65(see FIGS. 3 and 6). A coil spring 110 around shaft 109 bears on theratchet and urges it toward an initial, cleared, or starting positionshown in FIG. 3, at which the ratchet abuts the boss 108 on the lookbottom 34.

From FIG. 6 it can be seen that as the ratchet is advanced in thedirection toward the lock top 35, the pin 100 is passed in sequencethrough the sliders 84, extending through the holes 98 therein. As willbe seen, the holes 98 are positioned in the sliders to align with thepin as the pin is advanced; the positions of the holes are those in linewith the pin at the whole number settings of dial only at which the dialcan be pushed in. The ratchet 106 is sequentially advanced by push-inmovement of dial 23 through a stepping or advancing pawl 112 shown inFIG. 3, and is held in each position of advancement by a holding pawl113, shown in FIG. 6.

As best shown in FIGS. 2, 3, and 5, the stepping pawl 112 is pivotallymounted on flapper 50 on a shaft between two cars or legs 115 and 116,and has a tip which is shaped to interfit in the ratchet notches 107,toward which position it is urged by a biasing spring 119. An outer endportion of the stepping pawl extends through an opening formed in theflapper 50, and is positioned for engagement by a stepping pawl releasecam 121 on the case bottom 34. Such release is illustrated in FIG. 13,wherein it can be seen that when arbor 33 is pulled out, it moves theflapper 50 toward bottom 34- so that cam 121 engages and cams steppingpawl 112 out of engagement with the notches 107 on ratchet 106, so thatthe stepping pawl then exerts no force on the ratchet.

When arbor 33 is pushed inwardly flapper 50 is moved toward the top 35(see FIG. 11), and the stepping pawl 112, engaged in one of the notches107, exerts an axial force on ratchet 106 which moves the ratchetupwardly toward the lock top 35. It is thus the function of the steppingpawl 112 to advance the ratchet; it is the function of the holding pawl113 to hold the ratchet in any incremental psition to which it has beenadvanced by the stepping pawl. As best shown in FIGS. 2, 5 and 6, theholding pawl 113 is pivotally mounted on the lock midplate 64 betweentwo ears 124, 125 formed thereon. A holding pawl biasing spring 126urges the tip of the pawl into engagement with a notch 107 on ratchet106. When flapper 50 is pushed into advance the ratchet, movement of theratchet cams the holding pawl 112 out of one notch and it drops into thenext lower notch. When the flapper 50 is returned to centered psition(i.e. when the push-in force on the dial is released), the holding pawl113 engages and holds the ratchet position while the stepping pawl 112is cammed out of one notch 107 and drops into the next lower notch.

Holding pawl 113 has an outer end portion 127 which extends into anopening in the flapper (see FIGS. 2, 5 and 6) and is disposed to beengaged by a holding pawl release cam surface 128 on the flapper whenthe arbor is pulled out. This operation can be seen in FIG. 14. Pulloutmovement on arbor 33 swings flapper 50 toward lock bottom 34, andsurface 128 cams holding pawl 113 out of engagement with ratchet 106.Since pull-out movement on the arbor also causes the stepping pawl 112to be cammed out of engagement with ratchet 106, as explained above, theratchet is then moved by spring 110 to the starting or home positionshown in FIG. 3.

Clearance is provided in midplate 64 for movement of the respectivepawls, as shown in FIGS. 6, 11 and 14. Together, the stepping andholding pawls 112 and 113 cooperate with the ratchet 106 to providesequential advancing means for moving pin 100 in increments through thestack of sliders 84 in response to push-in movements of the arbor. Theratchet notches 107 are sized to effect an advancement of the ratchetequal to the thickness of one slider and spacer pair. Advancement of thepin through all the sliders is illustrated in FIGS. 6- and 7, FIG. 6illustrating the position of the pin when it is engaged with the firstslider only, while in FIG. 7 the positions ofthe components are shownwhen the pin has been advanced to hold all the sliders in place againstmovement responsive to the cam followers 83.

The set of fence members, each designated by 85, corresponds in numberto the number of ca-rn disks, cam followers, and sliders. Each member 85has a gate 97 with which the tooth 96 of the respective slider isinterengageable. As shown in FIG. 4, the individual members 85 may begenerally rectangular in form, and (when released) are slidable along apath parallel to the movement of the sliders '84, on a sleeve 132 whichpasses through slots 133 in the members. As can be seen from FIGS. 6 and7, the sleeve 132 is brazed or otherwise fixed at its end closest to thecase bottom 34, in a fence mounting means or block 134.

As seen in FIG. 6, the fence mounting means 134 includes an overhangingtop flange 136, against which the upper edges (as seen in FIG. 6) of theseparate members 85 reside. Thus, it keeps the members from cocking orturning around sleeve 132. The members are clamped against bracket 134by a fence lock shaft 137 having a cross pin 142 that engages sleeve132, the inner end of which is in turn secured to bracket 134. The headof shaft 137 bears upon a fence clamping leaf spring 138, which in turnpresses upon a pressure plate 139. Pressure plate 139 is juxtaposed withthe uppermost member 85.

As seen in FIG. 6, the lower end of fence lock shaft 137 is providedwith a tip portion 141 that projects beyond mounting means 134, forengagement by a bolt lever to be described. The cross pin 142 of theshaft 137 cooperates with a series of contiguous slots in the sleeve 132(see FIGS. 6, 7, and 9) to alternately hold the fence members in fixedposition, or to release them for sliding movement relative to oneanother. When pin 142 is aligned in the shorter slot 143 in sleeve 132,the fence members are clamped in place; when shaft 137 is turned so thatthe pin 142 is released from the short slot 143 and moved into thelonger slot 144 the compression of spring 138 is released and themembers are free to slide to the extent permitted by their slots 133.

A boss 146 (see FIG. 6) on the lower side of mounting means 134 has atongue 148 that projects into a slot 149 formed in midplate 64. Thefence pack is supported and guided for sliding movement toward and awayfrom the sliders by the tongue 148 in slot 149, and by ribs 147 (seeFIG. 9) formed on the midplate adjacent the edges of bracket 134. Thefence pack, including the individual members 85, shaft 137, mountingmeans 134, and associated structure, is slidable relative to themidplate, between the disengaged position shown in FIGS. 4 and 6, inwhich the gates 97 are disengaged from and out of contact with the teeth96, and the engaged position shown in FIG. 7 in which the teeth 96 areeach received in and interfit with the respective gates 97. Suchinterengagement can occur only if the sliders are in positions in whichthe individual teeth are aligned with the gates.

A fence biasing spring 150 bears on the projecting boss 146 of the fencemounting means 134, and urges the fence assembly toward the slider teeth96. When the fence members are engaged with the respective slider teeth,as shown in FIG. 7, it can be seen that the slotted head of shaft 137 isaccessible through an aperture 151 formed in the top surface 35 of thelock case cover 30, so that the shaft can be turned by a screwdriver.

In essence, the combination of the lock is determined by the positionsof the respective gates 97. The gates are typically set in positions ofdisorder, so that the slider teeth must be set at different positions toalign with and interfit with the respective fence gates.

Contact of the fence members with the slider teeth 96 during setting ofthe combination is prevented by engagement of the fence lock shaft tipportion 141 with a bolt lever designated generally at 155. This element155 is best seen in FIG. 5, and at one end is pivotally connected as at156 to the bolt 21. This lever has a leg 157 the end of which rests on aflat surface 163 of pin bracket 105 until the ratchet has been indexedto engage pin with all the respective sliders (see FIGS. 5 and 6). Atthe end opposite from pivot 156, lever 155 has a nose 158 that is shapedto interfit with the notch 73 of the bolt thrower or bolt throwing cam72 when aligned therewith. A leaf spring 159 constantly bears on thelever 155 so that leg 157 thereof rides upon surface 163 of the pinbracket 1'95, tending to move nose 158 toward the periphery of the boltthrowing cam 72 (see FIG. 2).

Lever 155 is provided with an angulated slot 161 having a width equal tothe diameter of shaft tip 141. When the bolt is extended, as shown inFIG. 5, tip 141 resides in this slot so that the fence members to whichshaft 137 is connected are prevented from moving toward the sliders. Theslot 161 is positioned or located so that clearance is maintainedbetween the fence members and sliders, and between the lever nose 158and the bolt thrower periphery, so long as leg 157 rides on surface 163.This prevents any possibility of detecting contact between the teeth 96and the fence members.

As seen in FIG. 6, the surface 163 of pin bracket is in a plane parallelto the axis of pin 1% and shaft 109. As a result, when ratchet 166 isindexed to arrest the respective sliders 84 this surface 163 slidesbeneath lever leg 157 without swinging lever around its pivot 156. Thus,engagement of lever nose 158 with the periphery of the bolt throwing cam72, and contact of the slider teeth 96 with the respective tumblers 85,does not occur during indexing of the sliders while the combination isbeing run. As also seen in FIG. 6, at the lower end of pin bracket 105,adjacent lock case bottom 34, there is provided an angulated or camsurface 164 leading from flat 163. When the pin is indexed to engage thelast slider, lever leg 157 is dropped off the angulated surface 164 (seeFIG. 7). Under the influence of spring 159, the lever thereby movestoward the bolt throwing cam, and it carries the fence pack toward thesliders. If the slider teeth are all aligned with the respective gates,lever nose 158 will under these circumstances engage the bolt throwingcam 72. If any of the sliders is disaligned, it will hold the lever noseoff the periphery of cam 72.

Bolt 21 is received for sliding movement in guides or ways formed in thelock base 28 (see FIGS. 3 and 5). The pivot member 156 by which lever155 is connected to the bolt has an enlarged head 1 67 which slides in aT-shaped slot 168 formed in midplate 64. The slot guides the bolt andprevents it from cocking as it is moved between extended and withdrawnpositions.

By reference to FIGS. 3 and 8, it can be seen that the flapper pivots 51are received or journalled in spaces defined between projecting ribs orbosses 170; and 171 formed on the lock base 28 and midplate 64respectively. As previously explained, the flapper springs 53 and 54 aretorsion springs encircling the flapper pivots 151 and they act inopposition or buck one another, thereby urging the flapper toward theneutral or centered position shown in FIG. 3.

OPERATION IN RUNNING THE COMBINATION Assuming that at the start the lockis in the position shown in FIG. 3, with the sliders and fence membersin disarray, setting the combination is started by turning the dial 23to the first number of the combination. As previously expressed, thiscan be done by turning the dial in either direction, that is, eitherclockwise or counterclockwise, directly to the number. No prescribedprogram of 1 1 numbers of turns, or of movements in alternatingclockwise and counterclockwise directions, need be followed.

Rotation of the dia is imparted to cam shaft 59 and and cams 79 throughthe universal ball joint incuding the balls 57 and ball grooves 56. Asthe cams rotate, the cam followers 83 follow the peripheries of thecams, and correspondingy cause the respective sliders to be movedlaterally on the posts 94. The springs 89 urge the cam followers towardthe cams, and the springs 95 hold the sliders in engagement with the camfollowers, so that the sliders are positioned according to the dialsetting. When the dial is at the desired number, the number is set bypushing the dial inwardly. This can be done only at precise or wholenumber dial positions, and not at intermediate positions, for unless thedial is at a position at which push-in stud 45 on the frame is alignedwith one of the push-in notches 44 on the driver flange 39, the studwill block push-in movement. This prevents restriction of the effectivenumber of possible combinations, since the lock will not respond tointermediate dial settings.

Assuming, then, that the dial is at an integer setting, pushing in onshaft 33 causes the flapper 50 to be pivoted clockwise (as seen in FIG.3) about its pivots 51. In the manner previously described, the stepingpawl 112, which is engaged with the first notch 107 of ratchet 106,shoves the ratchet incrementally toward top surface 35,, and the holdingpawl 113 drops into the second notch of the ratchet. Further push-inmovement of flapper 50 is limited by a stop (not shown) on the dial.When the push-in force on the dial is released, the flapper is returnedto its neutral position by its biasing springs 53 and 54. As this occursthe holding pawl 113 prevents the ratchet from sliding back to startingposition under the influence of the ratchet spring 110, and the steppingpawl 112 drops into the second notch of the ratchet.

Advancing of the ratchet by this first push-in or indexing motion movespin 100 an increment sufficient to cause it to engage one of the holes98 in the first slider 84, and thereby holds that slider against furthermovement. Thereafter that slider remains set at the same position, andif the number to which the dial has been turned is the true first numberof the combination, in that position the tooth of the first slider willbe aligned opposite the gate 97 of the first fence member.

The combination setting operation continues in similar fashion until allof the numbers of the combination have been dialed and set into thelock. The holes 98 are so positioned in the sliders that when the dialis set at any whole number position a hole 98 will be in alignment withthe pin 100 and the slider is arrested in such position. Further, theratchet notches 107 are dimensioned so that each push-in on the flapperadvances the holding pin 100 from one slider to the next.

When the seventh or last number of the combination is dialed and thedial is pushed in, the final advancing movement of the ratchet 106carries camming surface 164 from beneath the lever leg 157, and thelever 155 is permitted to drop from that surface. Such lever movement isimparted to the fence pack by the inter-engagement of fence shaft tip141 in the lever slot 161. If, as is assumed for this example, thecorrect combination has been set into the lock, then all of the sliderteeth 96 will be correctly aligned opposite the disarrayed fence gates97, and as the fence pack is moved toward the sliders, these willinterfit, and the siders do not block the drop of the lever. Hence thelever nose 158 drops onto the periphery of the bolt throwing cam 72.

As a final step, dial 23 is turned to a predetermined or constant finalposition (typicaly zero position), which brings the bolt throwing camnotch 73 into alignment with the lever nose 158, and the lever nosedrops into the notch, thereby connecting the lever to withdraw the bolt.Further counterclockwise rotation of arbor 33 (as seen in FIG. camslever 155 to the left, As this occurs, it

12 an be seen that the fence shaft tip 141 slides in the lever slot 161,and the lever leg 157 moves to the left off of the ratchet surface 165.Continued arbor rotation withdraws the bolt.

The bolt is extended by opposite rotational movement of the driver.Coaction of lever nose 158 with the edge of notch 73 earns the lever outof the notch. Simultaneously, engagement of the pin 141 in slot 161 camsthe fence pack away from the sliders, and lever leg 157 is lifted fromsurface 165. When the bolt is extended, the lower surface of the leg 157is substantially aligned with the camming surface 164. With the boltextended, the lock is cleared by pulling outwardy on dial 23. Suchpull-out axial motion or the arbor is limited to a position, such asdial zero position, at which the pull-out stud 46 on the lock case isaligned with the pull-out opening 47 in the driver flange.

When arbor is pulled out, the flapper moves the stepping pawl 112 intoengagement with the stepping pawl release cam 121, and the pawl is swungout of the ratchet notches. Similarly the camming surface 128 on theflapper disengages the holding pawl 113 from the ratchet notches. Theratchet is then free to move to its original or starting position underthe bias of the spring 110. As the ratchet returns to starting position,camming surface 164 earns the driver leg 157 onto the flat 163, thefence members are disengaged from the respective teeth, and pin isbacked out of engagement with all of the respective sliders. As thesliders are released, they are again moved into engagement with theirrespective cam followers, and their positions are again determined bythe cams.

From the foregoing it can be seen that in setting the combination thesliders are moved from starting positions of unknown disarray, topositions of known disarray corresponding to the combination, and thatwhen the lock is cleared, they are returned to positions of unknowndisarray.

CHANGING THE COMBINATION The combination of the lock is dependent uponthe respective positions of the fence gates 97. An important feature ofthe preferred lock of this invention is that the combination can readilybe changed without dissassembly of the lock, and even without removal ofthe cover 30.

To change the combination, the previous combination must first be run inthe usual manner and the bolt withdrawn. The fence members are therebyinterfitted with the respective sliders. The head of the fence lockshaft 137 is now accessible through aperture 151 in lock cover 30 (seeFIG. 7). By rotating shaft 137 so that the clamping force on the fencemembers is released, the members are freed so that they can individuallybe moved to new positions, for lock shaft cross pin 142 rides in the lnger slot 144 of sleeve 132, and spring 138 shifts the shaft 137 so thatthe tip 141 thereof is disengaged from the lever slot 161. The bolt isthen extended, but the fence members are now disconnected from the leverand therefore are not lifted out of their engagement with the sliders.Next, the new combination is run in the ordinary manner, with the boltextended. However, as the new combination is run, not only do thesliders follow the camming movement of the cam followers, but the fencemembers are also shifted by the sliders and follow the slider movement,so that the fence members are positioned in accordance with the cams.Stepping of the ratchet holds each slider by the engagement of pin 100in a hole 98, as stated earlier.

When the new combination has been run, the bolt is again withdrawn,shaft 137 is turned so that the fence members are clamped in their newpositions, and tip 141 is again positioned to couple the fence pack tothe lever. When the bolt is thrown and the lock is cleared, the fencemembers are lifted out of engagement with the sliders, in their newpositions.

Another feature of the present lock is that it can accept sliders and/orfence member of several different shapes, which have the teeth and gatesin different positions thereon. This individualizes each lock. Anotherdegree of individuality can also be built in by changing the positionsof individual cam disks 79 on the cam shaft from lock to lock. This canreadily be done in assembly of the cam disks on the cam shafts, sincethecams can be placed thereon in any of the several orientationspermitted by the interfitting points 80 and slots 81. This changes therelation of the dial to the fence gates, or the starting disarray, fromlock to lock, and in addition to the fact that the combination itself isvaried from lock to lock, this provides additional resistance againstsurreptitious attack.

For purposes of illustration, I have described herein a preferredexample of a lock construction embodying the features of this invention.However, those skilled in the lock art will recognize that the inventionis not limited to this embodiment alone, but is susceptible ofvariations and modifications including but not limited to use of otherinterfitting means on the tumbler elements or sliders, and the fencemembers, than the teeth and gates shown herein. For example, thepositions of the teeth and gates can be reversed; or other interfittingmeans can be used. Further, individual cam disks need not be used, butinstead an axially symmetric cam may be provided. Use of pivotallymounted cam follower engaging tumbler elements in place of the slidersshown is also envisioned.

I claim:

1. A combination lock comprising,

rotatable cam means,

a set of cam followers cammed by rotation of said cam means,

a set of movable elements biased toward engagement with the respectivecam followers for movement therewith,

a set of members interfittable with the respective movable elements ifthe respective movable elements are in predetermined positions ofalignment with respect thereto,

holding means engageable with each said movable element to arrest saidelement and thereby prevent said element from moving with the respectivecam follower,

means for cumulatively engaging said holding means with the individualmovable elements,

a bolt,

a lever connectable to withdraw said bolt,

and means responsive to movement of said lever to move said memberstoward the respective elements, said members having surface meansthereon engaging said elements to block connection of said lever towithdraw said bolt unless said elements are arrested by said holdingmeans in said predetermined positions of alignment with the respectivemembers.

2. A look in accordance with claim 1 wherein said movable elements arein the form of flat plates and are arranged as a pack.

3. A lock in accordance with claim 1 wherein said movable elements aremounted for linear sliding movement relative to one another.

4. A lock in accordance with claim 1 wherein said cam followers arelevers each having an area riding on said cam means and a second areaspaced therefrom contacting the respective movable element to cam thelatter in accordance with rotation of said cam means.

5. A lock in accordance with claim 1 wherein said cam means comprises anassembly of discrete disk-like cams engaged by the respective camfollowers and rotated together.

6. A lock in accordance with claim 5 wherein said lock has adial-operated cam shaft, and wherein said cams are keyed on said camshaft.

7. A lock in accordance with claim 6 wherein keying means are providedat spaced angular positions on said cam shaft so that said cams can bekeyed thereon in different orientations.

8. A lock in accordance with claim 1 further comprising ratchet and pawlmeans for moving said holding means in increments.

9. A lock in accordance with claim 1 wherein said holding meanscomprises a pin movable transversely to the movable elements, and aseries of holes in each said element in which said pin can interfit toarrest said element.

10. A lock in accordance with claim 9 wherein the shaft of said holdingmeans is mounted to a ratchet.

11. A look in accordance with claim 10 wherein said ratchet is moved bypawl means responsive to axial movement imparted to a shaft.

12. A lock in accordance with claim 11 wherein said ratchet is mountedfor movement along a path parallel to the axis of said shaft, and saidpawl means is actuated by a lever mounted to be swung by axial movementof said shaft.

13. A lock in accordance with claim 12 wherein said pawl means comprisesa stepping pawl moving said ratchet in response to axial movement ofsaid shaft, and a holding pawl holding said ratchet during return ofsaid stepping pawl.

14. A lock in accordance with claim 11 wherein said shaft is rotatableas well as axially movable and is connected to rotate said cam means.

15. A lock in accordance with claim 1 wherein said members are arrangedas a pack and are mounted for sliding movement toward said members.

16. A lock in accordance with claim 15 wherein said pack is coupled tosaid lever by a shaft cammed by movement of said lever.

17. A lock in accordance with claim 1 which further includes clampingmeans clamping said members together,

and means for releasing said clamping means when said members areinterfitted with said elements.

18. A lock in accordance with claim 17 wherein said clamping means alsocouples said set of members to said lever.

19. A lock in accordance with claim 18 wherein said clamping means alsoincludes structure decoupling said set of members from said lever whensaid clamping means is released from said members.

20. A combination lock comprising,

rotatable cam means,

an arbor for turning said cam means,

a set of cam followers cammed by turning of said cam means,

a set of movable elements biased toward engagement with the respectivecam followers for movement therewith,

holding means engageable with said movable elements to prevent saidelements from movnig with their respective cam followers,

ratchet and pawl means for advancing said holding means into holdingengagement with the respective movable elements in accumulatingsequence.

a set of members mounted for movement toward said movable elements,

interfittable means presented in part on said members and in remainingpart on said elements interfitting when said members are moved towardthe respective movable elements if all of said elements have beenengaged by said holding means in predetermined positions of alignmentwith the respective members,

a bolt and a bolt thrower,

a lever connectable with said bolt thrower for extending and withdrawingsaid bolt,

and means coupling said lever to said set of members to move saidmembers toward said elements when said lever is moved to connect it tosaid bolt thrower and to prevent said lever from connection to said boltthrower unless said interfittable means are interfitted.

21. A lock in accordance with claim 20 wherein said ratchet and pawlmeans includes a ratchet to which said holding means is mounted.

22. A lock in accordance with claim 21 wherein said ratchet and pawlmeans further includes a pawl operated by axial movement of said arbor.

23. A lock in accordance with claim 22 wherein said pawl is mounted to alever swung by axial movement of said arbor.

24. A lock in accordance with claim 23 wherein said *lever has a portionriding in a circumferential groove presented on means rotated by saidarbor.

25. A lock in accordance with claim 24 which further includes a stoplimiting axial movement of said arbor to an amount sufiicient to advancesaid holding means the dimension of one movable element.

26. A lock in accordace with claim 24 further including means preventingaxial movement of said arbor except at certain predetermined angularpositions thereof.

27. A lock in accordance with claim 26 wherein said preventing meansincludes a stud and an opening WhlCh must be aligned with one anotherfor said arbor to be moved axially.

28. A lock in accordance with claim 22 which further includes means forreturning said ratchet to a starting position in response to an axialmovement imparted to said arbor the direction opposite that foradvancing said ratchet.

29. A lock in accordance with claim 28 wherein the ratchet returningmeans includes a ratchet biasing spring and a pawl release cam.

30. A lock in accordance with claim 29 which further includes means forpreventing such opposite axial movement of said arbor, except at asingle predetermined angular position thereof.

31. A lock in accordance with claim 22 which further includes opposedsprings biasing said arbor axially to astarting position.

32. In a combination lock including a set of movable tumbler elements,means for positioning said tumbler elements comprising,

rotatable cam means,

a set of cam followers biased toward engagement with said cam means,

means biasing said tumbler elements toward engagement with therespective cam followers for cammed movement therewith,

movable holding means engageable with the respective tumbler elements toprevent them from moving with the respective cam followers,

and means for advancing said holding means to cumulatively engage therespective tumbler elements one by one.

33. A lock in accordance with claim 32 wherein said holding meanscomprises a shaft insertable in openings in said tumbler elements.

34. A lock in accordance With claim 32 wherein the means advancing saidholding means includes a ratchet advanced by axial motion imparted to alock dial.

35. A lock in accordance with claim 32 which further includes structurepermitting advancement of said holding means only at predeterminedpositions of said cam means.

36. A combination lock having a bolt,

a lever connectable to withdraw said bolt,

movable tumbler elements,

means for positioning the respective tumbler elements,

means for holding the respective tumbler elements against furthermovement when they have been positioned,

fence means blocking connection of said lever to withdraw said boltunless said movable tumbler elements are held in predetermined positionsof alignment with respect to said fence means and said fence means areinterfitted with said tumbler elements at such positions,

means movably coupling said fence means to said lever for moving saidfence means toward said tumbler elements in response to movement of saidlever toward connection to withdraw said bolt, said coupling meanspermitting movement of said lever with respect to said fence means andtumbler elements when they are interfitted with one another,

and means preventing such moving of said fence means toward said tumblerelements until all of the respective tumbler elements are held by theholding means.

37. A combination lock in accordance with claim 36 wherein said fencemeans comprises a set of individual fence members fixed in staggeredpositions with respect to each other.

38. A combination lock in accordance with claim 37 which furtherincludes means for changing the positions of said fence members withrespect to one another to change the combination of the lock.

39. A combination lock having a bolt,

a lever connectable to withdraw said bolt,

a set of movable tumbler elements and dial-operated means forpositioning said tumbler elements,

a set of fence members connected to said lever, each said fence memberbeing associated with a respective tumbler element,

each said tumbler element presenting one of a gate and a toothreceivable in a gate, each said fence member presenting the other of thegate and tooth than the respective tumbler element,

means holding said fence members in predetermined positions with respectto one another,

selectively operable means for changing the positions of said fencemembers with respect to one another while said teeth are received in therespective gates,

and means for moving said lever relative to said fence members when saidlever withdraws said bolt.

40. A lock in accordance with claim 39 which further includes meanspreventing contact between said fence members and tumbler elements untilall of said tumbler elements have been positioned.

References Cited UNITED STATES PATENTS 86,908 2/1869 Cole et al 708O247,250 9/1881 Hall 70-322 2,126,063 8/1938 Van Dine et al 70292,925,726 2/1960 Miller 70333 3,196,643 7/1965 Moss 70-133 3,357,21612/1967 Cook 70313 3,383,887 5/1968 Harris et al 70305 3,416,337 12/1968Hotchins 70284 FOREIGN PATENTS 16,822 1906 Great Britain.

MARVIN A. CHAMPION, Primary Examiner R. L. WOLFE, Assistant Examiner US.Cl. X.R. 70315

